Mode of preventing the explosion oe steam-boilebs



Sheets-Sheet 11.

WRIGHTIV Indicing--Skafety *.Guard 'for' Stem Bilers. MNO. 3,923- NPatented Feb; 24. 1845.

. zsheefS-sheez. w@ M. WRIGHT.

indicating Safety Guard for Steam Boilers.

No. 392s. Patented Feb. 24, 1845i UNITED STATES IPATENT OFFICE.

WILLIAM M. WRIGHT, OF PITTSBURGH, PENNSYLVANIA.

lVIODE OF PREVENTING THE EXPLOSION 0F STEAM-BOILERS.

Specication of Letters Patent No. 3,928, dated February 24, 1845.

To all whom t may concern Be it known that-I, I/VILLIAM M. IVRIGI-rr, ofPittsburgh, Pennsylvania, have invented a new and useful machine forpreventing the explosion of steam-boilers, consisting of the followingapparatus, to be called the indicating safety-guard, exhibited in theannexed drawing.

A tube A of brass or other met-al of high expansive power is screwed, orinserted, into the plate W and passed into the boiler E through theboiler head F and' extended along the flue G and held in its place bystaples loosely enough to enable it to move through them with facility.Into this tube A, which is to be steam tight is inserted a rod B of ironor other metal of less eX- pansive power, than that of which the tube iscomposed extending to and secured or inserted into the head of the tubeat Gr and long enough to project beyond the boiler head. This rod isattached by its outer end to a pointer called an indicator. Thisindicator is attached (so as to niove readily from and toward theboiler) to a stanchion I, projecting` from the plate JV and extends highenough or in any suitable direction to reach a dial J, upon which it jBy the heat of the boiler, th-e tube expands,

is to move as a hand.

. The dial is graduated into suitable divisions exhibiting the degreesof heat and pressure of the boiler and may be located where it isconvenient.

From the plate W, at a convenient point, projects a hinge K, extendingbeyond the indicator; to the end of this hinge is attached the chain orsaltus balance suspended from the end of the lever L of a safety valveM.

The chain should be so hooked to the point of the hinge, as readily todetach itself when the hinge iiies up. This hinge is to have a lateralor other projection O, so constructed as to catch upon a projection Pupon the indicator and prevent it from ris ing, as it otherwise would doby the force of the lever; and it (the hinge) must be heavy enough atthe end by its own or a suspended weight to fall very suddenly (whent-he catch on the indicator passes the catch on the hinge); so that itmay avoid the projection on the indicator, which will immediately returnoutward as soon as the steam begins to blow off, owing to the suddenreduction of `the temperature of the boiler and consequent contractionof the tube.

The plat-e IV with apparatus attached to ity is to be screwed on theboiler as by this means but one hole may be necessary in the boiler forthe insertion of the tube.

To insure the effectual relief of the safety valve, there is to be anupright fulcrum R (see No. 2) with a mortise in the upper end wide anddeep enough to enable the lever L of the valve (which is to pass throughit) to play freely in it. This fulcrum is placed between the valve andthe long end of the lever. The short end of the valve-lever L 1 insteadof being permanently fastened by a pin or rivet to the stanchion T asusual is 3 to lie upon it and the stanchion T is to have a slightmortise or indentation to keep the end of the lever, lying on it, in itsposition. To hold the short end of the valve-lever down a counter leverU passes over it at the stanchion T. The short end of this counter leveris fastened by a rivet to, and supported by, a stanchion V, so as freelyto play up and down. The long end of the counter lever U is held downby, and attached to, the indicating apparatus; with this appa-` ratusthe loading of the lever of the safety l valvev ever so much, isimmaterial.

The operation of my invention is this:

and lengthens more than the rod, and draws vthe rod inwardy and causesthe indicator to traverse the dial, and indicates on the dial,

boiler; and when the projection P upon the indicator, is thus drawn pastthe projecting catch upon the hinge, the hinge suddenly flies up anddisengages itself from the chain and completely relieves the pressure onthe valve. from the valve, the instantaneous contraction of the tube bythe cooling of the boiler causes the indicator to traverse the dial inthe contrary direction and exhibit the decreasing heat.

The apparatus adjusted.

Theboiler itself might be used as a tube, by running a rod through andattaching it to the opposite boiler head; in which case however, the rodwould have to be made of brass, or some metal of greater or less eX- maybe immediately As soon as the steam issues pansive quality, than themetal of the boiler and the project-ions on the hinge and indiof caststeel and hardened so as to prevent wearing; and that on the hingeshould be constructed so as to move readily upon the hinge inward andoutward; and attached to the hinge by a screw and nut, at anydeterminable point necessary to indicate the required heat and pressureupon the boiler.

The best position of the tube and boilers, which are made with flues isalong the outside of one of the flues, so high, as that the upper sideof the tube, may range horizontally with the top of the flue, and inboilers wit-hout flues, so that the upper side of the tube, may rangewith the fire line; by which means, when the water sinks to t-he iireline, the increasing heat, arising from the deiiciency of water, isimmediately shown, by the moving of the indicator and the relief of thesafety valve.

This whole apparatus may be so incased as to be entirely out of thecontrol of the engineer.

The degree of heat at which the apparatus goes oif, and thecorrespondent pressure which, may be desirable on the boilery is readilyascertained, by immersing the rod and tube of the apparatus as connectedwith the plate, in an oil bath, and by means of a thermometer of highrange, marking the degree indicated by the pointer on the dial, at whichit is desirable to have the apparatus operate, and fixing the projectionupon the hinge accordingly.

The indicating safety guard may be made to adjust itself after it hadblown off any proposed quantity of steam by the Jfollowing contrivanceas exhibited in drawing No. 3.

Resezttz'ng diaporama-The chain of the safety guard lever being securelyfastened t0 the end of the hinge H (in drawing No. 1 and When the hingeflies up and relieves the safety valve it is gradually pressed back toits former position by the vertical lever L. This lever L is held inposition by a st-anchion S, proceeding from the indicator and works upona pin in the fulcrum stake F, fixed into the plate W. As soon as thehinge K flies up and the cooling of the boiler causes the indicator tomake its counter movement which it immediately does, the lever L movesoutward upon the hinge and gradually presses it down over the catch P,to its former position.

To prevent the hinge being caught by t-he catch P on the return movementof the indicator the inner half of the catch P, is sloped from belowlike an inclined plane upon which the hinge when it iiies upward isthrown out from the indicator far enough to ride upon and over the outerpart of the catch thereby enabling the lever L to force it graduallyback to its original position.

To enable the hinge to fly past the catch P, on the machine going off amortise or opening is necessary in the hinge wide enough to admit thecatch to pass through the hinge as it flies up, which occurs as soon asthe motion of the indicator brings the catch P7 over the mortise.

Logo/motive slide valija- A mode of relief most suitable to locomotiveengines is a slide valve as exhibited at Figs. 2 and 3, Drawing No. 3.The open end of a shorttube T, is passed into the boiler, in which is anopening at I. @ver this opening and in a. dovetailed mortise works aslide M with a similar opening. This slide is attached to the indicatorby a nut and screw as at moving in a short sloat in the slide. Vhen theincreasing heat of the boiler moves the indicator it draws the slidewith it and brings the openings over each other and permits the steam toescape. As it is proper however that a portion of the steam should beblown off to reduce the temperature before the return motion of theindicator shoves the slide back andl closes the opening into the tube;the steam continues to escape until the indicator reaches the end of thesloat andeshoves the slide forward. The length of the sloat in the slidecan be increased or decreased by a plate and screw.

To give the indicator a greater range a counter pointer may be used asin Fig. 2, drawing No. 1. The expansive power of the tube and rod may besecured, the rod being made of the most and the tube of the leastexpansive power and that they may be constructed of any materials ofsuch diversity of expansion. The apparatus will of course be variedaccordingly.

What 1 claim as my invention is- 1. The modes of liberating andreclosing the valves in combination with the expansion tube and rod, therod being hermetically attached to the inner end of the tube by whicharrangement a stuiiing box for establishing the connection between theinside and outside of the boiler is dispensed with as described.

2. I also claim so connecting t-he safety valves with the expansion rodas to reclose the valve by the contraction of the metal after a givenquantity of steam has blown off as herein described.

WVM. M. WRIGHT.

Witnesses B. R. MoRsELL, H. R. NARYMAN.

